Braking mechanism



y 2, 1940- B DICK 2,206,030

' BRAK-ING MECHANISM Filed Nov. 14, 1938 2 Sheets-Sheet 1 INVENTOR: i

gums D/C'K BY H/S' ATTORNEY.

July 2, 1940. B. DICK BRAKING MECHANISM 2 Sheets-Sheet Filed NOV. 14, 1938 INVENTOR:

NS D/CK ATTMX Patented July 2, 1940 2,206,030

BRAKING MECHANISM Burns Dick, Ferguson, Mo., assignor to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application November 14, 1938, Serial No. 240,239 11 Claims. (Cl. 188-795) My invention relates to braking mechanism and more particularly to the mountingof the brake shoe or shoes within the drum.

, It has heretofore been proposed to so anchor smoother operation. The angle of the cooperating surfaces is also such as to cause each shoe to move transversely of the drum radius which bisects sthe shoe, indicated by the dash line X for shoe g one end of a brake shoe that said shoe is free to 5 have a pivotal movement to engage and disen- The ends of the shoes are maintained in posigage it from the. drum and to also have an autoen 011 be 6 and 7 y means of the s matic adjustment toward the drum at the anem I d 3 a d the anchor D Carries a Spring chored end to compensate for wear of the lining. I for holding the lower ends of the shoes in fric- 10 However, in this brake construction the oif" onal engagement wit o e not e A Be 10 position clearance between the lining at the free p 5 ho ds he Sp in l s t one shoes end of the shoe and the brake drum increases as 3 and 4 Carry linings 6 d an t e pp the lining wears. ends of the shoes are adapted to be expanded One of the objects of my invention is to proo en men w e drum y ns 01 a it vide means for association with a brake shoe fluid motor l8 which is actuated by fluid under of the type referred to whereby the end of the pressure from a suitable source. I shoe will be automatically maintained at a prede- When the fluid motor l8 in the type of brake t i distance from th drum hen in "o just described is actuated to move the upper ends position, said means being operable as a result of the brake shoes into engagement with the Q0 of the movement of the anchored end of the shoe drum, each shoe will pivot about anchor pin 5 t d th d um, and engage the drum in the same manner as it Still another object of my invention is to prowould if the block were eliminated and the shoe vide means whereby the retracting force applied directly pivoted on the anchor pin as is common tothe shoe to return it to "011! position will not practice. If the drum is rotating in the direction tend to cause the anchored end of the shoe to indicated by the arrow, shoe 3 when engaged will shift bodily relative to its pivot and away from have a force acting on its anchored end tending the drum as the shoe assumes its ofi" position. to move it toward the drum and in a direction Other objects of my invention will become apcorresponding to the cooperating surfaces 8 and parent from the following description taken in 9, and I0 and II. The force acting to move the 80 connection with the accompanying drawings in lower end of the shoe toward the drum varies which Figure 1 is a view, partly in section, of a with the angle a and is a component of the selfbrake embodying my invention; Figure 2 is a energizing force acting on the shoe. As the lincross-sectional view taken on the line 2-2 of ing l6 of the shoe wears, the Wear will be com- Figure 1; and Figure 3 is a view similar to Figure pensated for by an automatic adjustment 'of 1 showing a modified construction. the anchored end of the shoe, this automatic ad- Referring to Figures 1 and 2, numeral I indljustment being caused by the force tending to 35 cates a brake drum which is fixed to the wheel of move the anchored end of the shoe toward the the vehicle and 2 the backing plate or support for drum. The adjustment causes a relative movethe brake shoes 3 and 4, this backing plate closment between the surfaces 8 and I0, and 9 and 40 ing the open side of the drum and being secured H and since there is frictional engagement beto some convenient fixed part of the vehicle, as tween the ends of shoes 3 and 4, the new posi- 40 for example, the axle housing. The backing plate tion assumed by shoe 3 during the adjustment on the lower side carries an anchor pin 5 and will be maintained. The adjustment is not dispivotally nt d th ar tw members 6 turbed by retraction of the shoe from the drum and 1 having parallel surfaces 8 d 9 f d as the shoe during retraction acts the same as thereon. The lower end of shoe 3 is formed with an ordinary pivoted shoe and only rotates about 45 a tch or 101; for receiving the m mb 6, the the anchor pin as it frees itself from the drum. notch having parallel surfaces 10 and II for co- When the drum is rotated in the opposite direcoperation with the surfaces 8 and 9, respectively, tion, shoe 4 will have the same action as shoe 3 of member 6. Similarly, the lower end of shoe and there will result an automatic adjustment 50 6 is provided with a notch or slot for receiving of the anchored end of this shoe to compensate member I. the slot also having parallel surfaces for the wear of lining l1.

Ill and II for cooperation with the surfaces 8 Since each shoe, during the automatic adjustand 9 on member 1. The surfaces 8 and 9 on ment, is moved outwardly toward the drum and members 6 and 'l and the cooperating surfaces in a direction corresponding to the direction of 55 I0 and II of the slots lie at an angle a with rethe surfaces 8 and Ill, and 9 and l I, the upper or spect to a diameter passing through the center toe end thereof will consequently be moved downof the brake and the center of the anchor pin 5, wardly away from the drum. This movement of this angle being preferably such as'to cause the the toe of the shoe, in addition to the wear of an shoes to have an increased braking torque and the lining over the entire shoe, causes a variable off" position clearance between the shoe lining and the drum, especially at the end of the shoe unless some means are provided to keep the clearance substantially constant. In accordance with my invention, I have provided the central portion of shoe 3 with an inclined surface l9 for cooperation with the adjustable stop carried by the backing plate. Also the central portion of shoe 4 is provided with an inclined surface 2| for cooperation with the adjustable stop 22 carried by the backing plate. Retractile springs 23 and 24 are provided for normally holding the shoes off the drum and the surfaces l9 and 2| in engagement with the adjustable stops 20 and 22. One end of the retractile spring 23 cooperates with the abutment 25 on the backing plate and the other end with a rod 26 passing through the coil of the spring and connected with the shoe. The spring is so positioned that the line of force acting on the shoe and tending to retract it from the drum is at right angles to the plane of surface |9 which cooperates with the adjustable stop 20. The retractile spring 24 for shoe 4 is of the same construction as the retractile spring 23 being interposed between the abutment 21 and the end of a rod 28 passing through thecoil of the spring and connected to the shoe. The line of force of spring 24 tendin to retract the shoe from the drum is at right angles to the plane of surface 2| cooperating with the adjustable stop 22.

The surface IS on shoe 3 is so related to the direction of movement of the anchored end of the shoe determined by the surfaces 8 and and 9 and II that as the lower end of the shoe moves outwardly toward the drum to perform the automatic adjustment to compensate for wear of the lining II, the other portion of the shoe, when in retracted position, will also be moved outwardly toward the drum an amount such as to maintain the toe end of the shoe at substantially the same distance from the drum as it was prior to any adjustment at the anchored end of the shoe. In other words, the angle of surface I9 is such as to insure that all portions of the shoe and especially the toe end of the sh when the shoe is in its off position, will be so positioned as to maintain a substantially constant clearance between the lining and the drum throughout the life of the lining.

The surface 2| of shoe 4 bears the same relation to the direction of movement of the anchored end of said shoe determined by the cooperating surfaces 8 and i0, and 9 and II as that just described with respect to surface l9. Thus as the lining of shoe I wears and moves bodily downward during the automatic adjustment of the anchored end, all portions of the shoe will be maintained at a substantially fixed distance from the drum when the shoe is in retracted position.

By the provision of the inclined surfaces |9 and 2| on the shoes, the brake shoes will be automatically adjusted throughout the entire life of the lining and each shoe will have an "off" position clearance which will be substantially constant throughout the life of the lining. Furthermore, by having the toe end of the shoe adjusted simultaneously with the anchored end of the shoe, it will not be necessary for the toe end of the shoe to be moved an excessive distance to engage the shoe with the drum, thus preventing any slack from developing in the actuating system and consequently insuring that there will be a uniformpedal travel throughout the life of the lining.

Since the retractile springs 23 and 24 act on shoes 3 and 4, respectively, with a force which is in the direction at right angles to surfaces l9 and 2|, there will be no force set up which will tend to effect the automatic adjustment of the anchored ends of the shoes.

The inclined surfaces |9 and 2| need not be placed at the central portion of the shoe as obviously they may be carried by the shoe at other points, it only being necessary that they have such relation to the movement of the anchored ends of the shoes that all portions of the shoes remote from the anchors will always be maintained at a substantially constant distance from the drums when the shoes are in retracted position.

It may be impossible in some brake assemblies, due to lack of space, to employ the type of retractile springs 23 and 24 shown in Figure 1. As shown in Figure 3, a retractile spring 29 may be employed between the upper ends of the shoes just below the actuating motor l8. The retractile force of this spring, of course. will not be at right angles to the inclined surfaces l9 and 2| on the shoes and, therefore, a force will be present tending to move the shoes upwardly. In order to insure that the adjustment of each shoe is not disturbed, I provide springs 30 and 3|. Spring 90 acts downwardly on the anchored end of shoe 3, being interposed between the shoe and the abutment 32. Spring 2| acts downwardly on the anchored end of shoe 4, being interposed between said shoe and an abutment 33. The springs 30 and 3| are of such strength and act in such direction as to neutralize the force of the retractile spring 29 tending to shift shoes 3 and 4 upwardly.

Being aware of the possibilityof other modifications in the particular structure herein de scribed without departing from the fundamental principles of my invention, I do not intend that its scope be limited except as set forth by the appended claims.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In braking apparatus, a brake drum and a brake shoe for cooperation therewith, said shoe being mounted at one end for pivotal movement into and out of engagement with the drum. means for automatically adjusting the 0113" position of the pivoted end of said shoe with relation to the drum by a force effective on the shoe during braking application when the brake lining thickness at the pivoted end is reduced by wear, said adjusting means being so formed and positioned as to cause the shoe to move, when the pivoted end is adjusted toward the drum, transversely of the drum radius which bisects the shoe. and wear compensating means spaced from the pivoted end of the shoe and functioning as the result of the aforesaid transverse movement to adjust the free end of the shoe toward the drum.

2. In braking apparatus, a brake drum and a brake shoe for cooperation therewith, said shoe being mounted at one end for pivotal movement into and out of engagement with the drum.

means for automatically adjusting the off posi-- tion of the pivoted end of said shoe with relation to the drum by a force effective on the shoe during braking application when the brake lining thickness at the pivoted end is reduced by wear, said adjusting means being so formed and positioned as to cause the shoe to move, when the pivoted end is adjusted toward the drum, transversely of 3. In braking apparatus, cooperating rotatable and non-rotatable members one of which is provided with a friction surface, said non-rotatable member being mounted at one end for pivotal movement and also for automatic adjustment toward the drum as said friction surface wears, and wear compensating means comprising means located at a point spaced from the mounted end of the non-rotatable member and operating in response to the movement of the non-rotatable member which results in adjustment of the pivoted end of the non-rotatable member toward the rotatable member.

4. In braking apparatus, a brake drum, a brake friction element cooperating with the drum and mounted atone end forpivotal movement and also for automatic adjustment toward the drum as the friction surface of the mounted end of said element wears, an off position abutment for the friction element, and means for automatically advancing toward the drum the ofi" position of the friction surface of the free end of said element relative to the abutment when the off position of the mounted end of the shoe is automatically adjusted toward the drum, said means comprising an inclined surface carried. by the shoe at a point spaced from the mounted end and engaging said abutment when the shoe is in off position.

5. In braking apparatus, a brake drum, a brake friction element cooperating therewith, said element being mounted for engagement with the drum by pivotal movement, the pivoted end thereof being automatically adjustable toward the drum to compensate for lining wear, and wear compensating means comprising means located at a point spaced from the mounted end of the shoe and functioning to automatically advance the off position of the body of the shoe toward the drum when the off position of the pivoted end of the shoe is automatically adjusted toward the drum.

6. In braking apparatus, a brake drum and a brake shoe for cooperation therewith, said shoe being mounted at one end for pivotal movement and also for automaticadjustment at said end toward the drum as the shoe surface wears at said end, and wear compensating means operating in response to the movement of the shoe resulting from automatic'adjustment of the pivoted end of the shoe toward the drum to automatically adjust the friction surface of another part of the shoe toward the drum.

'7. In braking apparatus, a drum, a brake shoe having a lining thereon for cooperation with the drum, means for mounting one end of said shoe for pivotal movement and also for automatic adjustable sliding movement toward the drum as the lining wears, means for actuating the element about its pivotal axis, means forming an inclined surface on the shoe at a point spaced from its mounted end, and an abutment cooperating with the inclinedsurface when the shoe is in retracted position, said surface extending in substantially the same direction as the direction of sliding movement of the mounted end of the shoe and causing said shoe to have a predetermined oif position clearance with the drum as the mounted end of the shoe moves toward the drum.

8. In braking apparatus, a drum, a brake shoe for cooperation with the drum, means for mounting one end of said shoe for pivotal movement l0 and also for automatically adjusting movement towardthe drum as the shoe wears, means for maintaining a substantially constant off" posi tion clearance between the shoe and drum, said means operating as a result of the movement of the mounted end of the'shoe toward the drum and comprising an inclined surface associated with the shoe at a point spaced from the mounted end, and spring means associated with the shoe and producing a retracting force acting at substantially a right angle to the inclined surface the drum.

9. In braking apparatus, a drum, a brake shoe for cooperation with the drum, means for mount-'- ing one end of said shoe for pivotal movement and also for automatic adjustment towardthe drum as the lining wears, and means comprising an inclined surface so associatedwith theshoe at a point spaced from its mounted end and so related to the direction of movement of the shoe end that all portions of the shoe will be main-' 7 tained at predetermined distances from thedrum when in off position and a retracting spring 7 ends of the shoes, means forming an inclined surface on each shoe, an abutment cooperating with each surface in the o position of the shoes,

said inclined surface on each shoe beingso related to the direction of movement of the mounted end of the shoe that a predetermined off" position clearance will be maintained between said shoe and the drum as the mounted end of the shoe moves toward the drum, means for retracting the shoes from the drum, a retracting spring connecting the actuated ends of the shoes and producing force on each shoe tending to move said shoe relatively to its abutment when the inclined surface is in engagement therewith, and spring means acting on each shoein a direction opposite to said force and with substantially equal magnitude.

11. In braking apparatus, a drum, abrake shoe for cooperation with the drum, brake shoe mounting and adjusting means for one end of the shoe and comprising means permitting pivotal movement of the shoe and means permitting adjustable sliding movement in a selected plane toward the drum to compensate for lining wear, and

means for automatically advancing a portion of the shoe remote from the mounted and toward the drum as the said mounted end is adjusted, said means comprising an inclined surface associated with the shoe at a point spaced from the 7 

